This invention relates to a heatable vehicle window (e.g., vehicle windshield) including at least first, second and third heating zones.
Heatable windows are known in the art. For example, see U.S. Pat. Nos. 3,893,234 and 5,229,205, the disclosures of which are hereby incorporated herein by reference. Conventional heatable windows for vehicles typically include first and second conductive bus bars in electrical contact with a conductive coating including an electroconductive layer. The first bus bar is usually provided at a top portion of the window, and the second bus bar at a bottom portion of the window. The electroconductive layer, at a location between the bus bars, generates heat when electric current is passed therethrough via the bus bars. In such a manner, snow and ice may be melted from vehicle windows such as windshields, backlites, sidelites, and/or the like. Windows may also be defogged in such a manner.
In recent years, devices such as rain sensors and/or toll devices have become desirable in vehicles such as cars, trucks, sport utility vehicles (SUVs), and the like. Rain sensors and/or toll devices are often mounted within the vehicle proximate a top portion of the windshield (e.g., near where rearview mirrors are sometimes located). Rain sensors and/or toll devices typically transmit and/or receive signals (e.g., infrared signals (e.g., 880 nm), RF signals, electromagnetic signals, etc.) through the windshield. Accordingly, it is undesirable to position signal inhibiting structures such as metal bus bars and/or conductive coatings in areas of a windshield through which such signals must be transmitted/received by rain sensors and/or toll devices. Unfortunately, if one were to simply modify the shape of the upper bus bar in a conventional heatable windshield to loop around the rain sensor and/or toll device area (e.g., see FIG. 4), then hot spots would tend to develop at corners/curved areas of the upper bus bar as the windshield is heated (i.e., the current flow is not approximately uniformly distributed).
In view of the above, it will become apparent to those skilled in the art that there exists a need in the art for a heatable window design which enables current flow to be approximately uniformly distributed, so as to reduce the likelihood of overheating and enable efficient heating of the window.
An object of this invention is to provide an efficient bus bar arrangement for a heatable vehicle window (e.g., windshield).
Another object of this invention is to provide a heatable vehicle window including at least first, second, and third heating zones. In certain embodiments, each zone includes its own heatable coating portion which does not extend into any of the other heating zones.
Another object of this invention is to provide a heatable window design which is capable of accommodating a rain sensor and/or toll device coating deletion area, without being susceptible to a high likelihood of overheating.
Another object of this invention is to fulfill one or more of the above-listed objects.
This invention will now be described with respect to certain example embodiments thereof as illustrated in the following drawings, wherein: